Happy New Year to all!
In working on my TM501 which serves as the power supply for my AM503B current
probe, I had to dismount the 2 series pass transistors from the TM case (heat
sink). After repair (filter caps) and during remounting the circuit board, Q12
transistor TO-127 case fractured whil
The mainframe power transistors are NOT darlingtons. They are plain NPN/PNP
power transistors with non-standard pinouts.
The non-high power slots are rated at least 15W (The PS503A power supply can
drop the 33V DC lines to 0V at 0.4A). The high power slots use normal TO-3
transistors rated
The parts are definitely not darlingtons (but then, I have only repaired over
1000 TM500 modules and mainframes...). Both junctions measure around 0.545V.
Just about any general purpose power transistor will work just fine. You want
devices rated at least 60V and 20W. I would tend to avo
Frankly, screw the idea of ordering $30 transistors or paying big shipping
charges from Canada. Just go to Ebay, find a cheap TM50X power module,
bingo! you're in business! Either use the module as-is or salvage the
transistors from it and repair the TM501.
TM501 modules are rather hard t
Ok, best solution looks like ebay item 230417555926. A TM506 mainframe for
$25+36 shipping. The mainframe includes two TM500 "toolbox" modules. Flip
the toolboxes back onto Ebay... they can bring around $15-$20 ea (there's
guys trying to sell them for $30-$40). Scrap the TM506 for tran
Isn't the pinout of the MJE3055 (BCE) different from the SJE924 (ECB).
Dave
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Don @ True-Cal
Sent: 02 January 2010 20:33
To: time-nuts@febo.com
Subject: [time-nuts] Tektronix TM500 S
o.com
Subject: [time-nuts] Tektronix TM500 Series Help
Happy New Year to all!
In working on my TM501 which serves as the power supply for my AM503B
current probe, I had to dismount the 2 series pass transistors from the TM
case (heat sink). After repair (filter caps) and during remountin
Don wrote:
The manual (and device) says Q12 is an NPN, SI, Selected, TO-127
SJE924. For completeness, the complementary Q10 is a PNP, SI, TO-127
SJE925. These transistors types are the same across any TM-Series mainframe.
I can't find any SJE or MJE 9xx reference. Does anyone have a cross
re
Try these guys:
http://www.sphere.bc.ca/test/
I've dealt with them for Tek parts in the past; they are quite good.
Don
- Original Message -
From: "Don @ True-Cal"
To:
Sent: Saturday, January 02, 2010 1:33 PM
Subject: [time-nuts] Tektronix TM500 Series Help
Happy
Mark wrote:
The mainframe power transistors are NOT darlingtons. They are plain
NPN/PNP power transistors with non-standard pinouts.
The TO-127 pinout is ECB -- most other plastic power transistor
packages are BCE.
I just pulled the cover off a TM503, and the 151-0349-00 (and
151-0373-00)
These external transistors are shown on the PS503 as single transistors,
and they are driven by a single stage transistor from an op amp.The
external pass transistors for each plug-in could use NTE182 (NPN) and
NTE183(PNP). IMHO, the hfe of the NTE devices will be entirely adequate,
and they're che
find a good source for the TO-127 MJE2801 (ECB) version, I will have to mount
it upside down.
Regards...
Don
- Original Message -
From: Don Latham
To: Discussion of precise time and frequency measurement
Sent: Sunday, January 03, 2010 3:28 PM
Subject: Re: [time-nuts] Tektron
Mark wrote:
The problem with ordering from Sphere is the prices. Their parts
tend to be expensive and the shipping is a killer ($22+ last time I
ordered) for a simple transistor. You can buy suitable replacements
for under $0.50 each.
Suitable in the sense of Pd, Vceo, Hfe, and Ft, yes. H
Don wrote:
1) The devices in any of my TM mainframes are NOT Darlingtons.
2) The actual Q12 device in my TM501 is stamped SJE924 (Tek PN 151-0349-00)
These two facts seem contradictory with copied Motorola Data Sheet
info but I going with what I see in front of me.
If you have a device marke
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